Polymers of vinyl substituted benzal acetophenones

ABSTRACT

Light-sensitive polymeric compounds are prepared by condensing a polymer or copolymer containing acyl groups with an aromatic aldehyde of formula QCHO, where Q is an aryl group of the benzene or naphthalene series (substituted or not).  Specified polymers are a  - naphthal -, isopropylbenzal -, p - hydroxybenzal-, p-dimethylaminoo-chlorobenzal-, p-acetamidobenzal-, p-sulphobenzal-, anisal-, and veratral-acetyl benzenes, polyvinylbenzal acetophenone, polyvinylanisal acetophenone and numerous others.  The acylated polymer is preferably a polymer of an acylated vinyl benzene or naphthalene which is then condensed with preferably an excess of the aromatic aldehyde in from about 1/10 to about 25 to 50 mols. of aldehyde per mol. of monomers in the polymers to yield the polyvinyl arylidene acetophenone.  Partially acetylated polystyrene, which may be used, is prepared by treating a carbon disulphide solution of polystyrene with acetyl chloride in the presence of ammonium chloride.  Alternatively an acetylated styrene copolymer may be obtained by copolymerizing a mixture of a vinyl acetophenone (which may be prepared by depolymerizing polyvinylacetophenone) with a compound containing a -CH=C&lt; group, followed by condensing acyl groups of the polymer with the aromatic aldehyde.  This condensation is carried out in the presence of a dehydration catalyst, e.g. sulphuric acid, phosphoric acid, acetic anhydride, phosphorus pentoxide, toluene sulphonic acid, trimethyl benzyl or tetramethyl or tetraethyl, or tetraethanol ammonium hydroxides, trimethyl benzyl ammonium butoxide, sodium hydroxide, or sodium methoxide in the presence of a solvent, e.g. 1,4-dioxane, benzophenone or a large excess of the aldehyde.  Specified -CH=C&lt; containing group compounds are styrene, acrylonitrile, vinyl acetate, vinyl ketones, vinyl ethers, methyl methacrylate, isobutylene and maleic anhydride. Specifications 695,197, [Group XX], 713,947, 717,708, 717,710, 717,711, 717,712 and 732,602 and U.S.A. Specification 2,566,302 are referred to.

United States Patent ce POLYMERS OF VINYL SUBSTITUTED BENZALACETOPHENONES 5 Cornelius C. Unruh and Charles F. H. Allen, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey No Drawing. Application September 13, 1951,

Serial No. 246,516

16 Claims. (Cl. 260-47) This invention relates to the preparation ofacylated vinyl polymers and more particularly to light-sensitivepolymers of vinyl benzal acetophenones.

In the Allen et a1. U. S. patent application, Serial No. 771,142, filedAugust 28, 1947, now U. S. Patent No. 2,566,302, granted September 4,1951, are described 20 light-sensitive polymers made by the acylation ofa polymer such as polystyrene with cinnamoyl chloride. Since acylationapparently proceeds to a limited extent, a

2,716,097 Patented Aug. 23, 1955 The polymers of our invention areprepared by condensing a polymer of acylated vinyl benzenes andnaphthalenes (acetylated ar-vinyl benzenes and naphthalenes in which thevinyl group is attached to an aromatic nucleus) with anuclear-substituted benzaldehyde. This is accomplished in several ways.A polymer containing aromatic nuclei such as a polystyrene, polyvinylnaphthalene, a-methylstyrene or a copolymer thereof is partially orcompletely acylated by the Friedel-Crafts reaction and the resultantpolymer is then condensed with preferably, but not necessarily, anexcess of the selected aromatic aldehyde of the order of from about ,5to about -50 mol of aldehyde per mol of the vinyl acetophenone monomerin the polymer, to yield the desired polyvinyl arylidene acetophenone.Alternately, a vinyl acetophenone, vinyl propiophenone etc. compound canbe homopolymerized or copolymerized with other compounds containing apolymerizable -CH=C group, particularly a CH2=C group, such as styrene,and the resultant polymer condensed with the aromatic aldehyde underconsideration.

The following reactions illustrate methods for carrying out ourinvention:

IV GB @COCH:

polymer is obtained such as one having the following formula:

Polymers obtained by this method in which the molecular ratio of unit Ato unit B is from 5:1 to 18:1 (16 to 5 mol percentvinylbenzalacetophenone units) are said to possess especially usefulphotographic properties including solvent solubility and lightsensitivity rendering the polymers particularly useful inphotomechanical processes.

We have discovered that if polymers of the above type are prepared inthe manner of our invention, they are not only more soluble in organicsolvents but possess much higher sensitivity to light.

R' represents a phenyl or a or 18 naphthyl group preferably substitutedWith one or more groups such as omethoxy, o-hydroxy, p-hydroxy, o-sulfo,o-chloro, etc.

R represents a group such as hydrogen, alkoxy and aryloxy e. g.o-methoxy, p-phenoxy, alkyl e. g. m. tort.- butyl and methyl, hydroxy e.g. o-hydroxy, halogen e. g. o-chloro, aralkyl e. g. p-benzyl. Thenucleus can also be substituted with more than one of such groups e. g.3,4-dichloro, 2,5-dimethyl, 2,5-dichloro, 3,4-dihydroxy, 2,3-dimethyl.Similarly such substituents may be present on a naphthalene nucelus whenpreparing the acylated vinylnaphthone polymers. When the polymer reactedwith the aldehyde or mixture of aldehydes is obtained by acylation of avinyl benzene or naphthalene polymer (method I and III) the acid halideused may be any one or a mixture of those containing 2-5 carbon atomssuch as acetyl, propionyl, butyryl and valeryl chlorides. Acetylchloride is preferred since the vinyl benzalacetophenone andacetonaphthone polymers are more lightsensitive than c. g. the vinylbenzalpropiophenone polymers. Where R is amino, hydroxyl, nitro, sulfoand carboxyl, methodsII and IV are preferred.

Likewise, according to methods II and IV, the carbon chain of the ketonegroup of the monomeric compound preferably contains 25 carbon atoms. TheWilliams U. S patent application Ser. No. 246,524, filed concurrentlyherewith, provides a convenient method for preparing these ketones forexample from p-ethyl acetophenone or p-ethyl propiophenone. When R ofthe acylated compounds is amino, hydroxyl, sulfo and carboxyl, methodsII and IV and the Williams procedure for preparing the ketone monomer isused.

In the formulas in the above chart the values for the integers n, n, n",and n are dependent'somewhat upon the molecular weight of the polymerreacted with the aldehyde. n" in methods I and II and in methods III andIV can be positive integers, or equal to zero in case all of the acetylgroups of the polymer have been reacted with'the aldehyde as shown inthe examples following. In the formulas it will be apparent that when amixture of aldehydes including benzaldehyde is reacted with the acylatedpolymer, the resultant polymer contains a mixture of vinylaralacetophenone units.

When the polymers of our invention are obtained as described, regardlessof the derivation of the particular acylated polymer which is condensedwith the aromatic aldehyde, the resultant products are in general moresensitive to light than those produced by the methods of the Allen eta1. invention. In making this comparison, sensitivity to light isdetermined by exposure of a layer of the polymer on a hydrophilicsurface under a photographic step tablet to insolubilize the polymer inthe exposed regions. removed with a solvent for the polymer such asmethyl ethyl ketone. The sensitometric characteristics of theundissolved polymer remaining in the form of a step tablet are thenrecorded by well-known photographic methods. From these values a speedvalue is assigned to the particular polymer under test. When tested bythis method, representative polymers of the Allen et al. inventionpossess speeds of from 1.4 to 7 (made by reacting from 1:5 to 1:18 molof cinnamoyl chloride per 7 mol of polystyrene) whereas none of thepolymers of our invention have speeds less than 7 and speeds of theorder of 1000 to 2500 and higher are readily obtained by selection ofthe proper reactants and conditions of reaction. A possible explanationfor the fact that the polymers of our invention in general possess suchrelatively higher light sensitivity, lies partly in a belief thatsubstantially no cross-linkages are formed in the polymers obtained byour methods. That is, it is believed that when a polymer containingaromatic nuclei iscinnamoylated by the methods of the Allen et a1.invention, the catalyst utilized induces the formation of cross-linkageswhich reduce light sensitivity and which tend to insolubilize thepolymer before very many cinnamoyl groups have been introduced into themolecule. On the contrary, by our methods we start from a polymercontaining the desired proportion of vinyl acetophenone units.Subsequent reaction of the polymer with an aromatic aldehyde appears toyield a polymer substantially free of crosslinkages. By our methods wereadily obtain polymers containing at least 21 mol percentof vinylbenzal acetophenone units and such resins, apparently due to theincreased number of unsaturated groups present and freedom fromcross-linkages, possess speeds of the order of 2500. Even 'vinyl benzalacetophenone polymers made from a copolymer such as a styrene-vinylacetophenone copolymer (Example 17) which contains substantially lessthan 21 mol percent of light-sensitive groups, is very light sensitive.On this speed evaluation scale well-known dichromated colloid systemssuch as dichromated glue have a speed of the order of 30.

After exposure, the least exposed areas are 9 Furthermore, since weutilize nuclear-substituted benzaldehydes in the reaction, thesubstituent on the nucleus of the aldehyde may be exerting a profoundeffect not only upon the course of the reaction but also may bepromoting the insolubilization of the polymer when it is exposed tolight and thus increasing the light sensitivity.

In general, the preferred polymers of our invention are polymers of acompound having the general formula:

wherein D represents an aryl group or the benzene or naphthalene seriessubstituted if desired as indicated above and Q is a phenyl or naphthylgroup, or naphthyl or phenyl group substituted, for example, with thegroups alkyl, alkoxyl, hydroxyl, halogen, acetamido, aryloxy, amino,sulfonic acid, etc.

For example, polymers of the following are contemplated by ourinvention:

Isopropylbenzal acetylstyrene p-Hydroxybenzal acetylstyrenep-Dimethylamino acetylstyrene o-Chlorobenzal acetylstyrene p-Acetamidobenzal acetylstyrene p-Sulfobenzal acetylstyrene Anisalacetylstyrene Veratral acetylstyrene Anisal acetyl-o-methoxystyrenep-Hydroxybenzal acetyl-o-methoxystyrene o-Chlorobenzalacetyl-o-chlorostyrene 1' p-Chlorobenzal acetyl-2,S-dimethylstyreneAnisal acetyl-p-phenoxystyrene Anisal acetyl-p-bromostyrene Tolualacetyl 3,4-dimethoxystyrene Anisal acetyl-o-fluorostyrene m-Naphthalacetylstyrene Anisal benzal-acetylstyrene Anisalvinylmethyl ketone Thelatter compound is representative of other lightsensitive benzal acetyland naphthal acetyl group-containing polymers made by condensingaromatic aldehydes with polymers containing acetyl groups, such as vinylmethyl ketone polymers and co-polymers. Other polymers also containingacetyl groups attached directly or indirectly to linear carbon atompolymer chains are utilized similarly. Anisal benzal acetylstyrene isrepresentative of polymers obtained by reacting a mixture of aldehydeswith the polymer containing acetyl groups.

Accordingly, the light-sensitive polymers contain the group in which nis a number from 1 to 4 and Q is nuclear substituted aryl group of thebenzene or naphthalene series and D is a single bond or aryl group ofthe benzene or naphthalene series. When n is 2 to 4 the structureobtained results from reaction of the aldehyde with the alpha methylenegroup of a ketone polymer such as polyvinyl propionphenone.

In general, the preferred polymers are obtained by condensing a polymer(homopolymer or copolymer) of a compound having the general formula:

wherein D is the same as above, in the presence of an acid or alkalinecondensation'catalyst, with a benzaldehyde, the nucleus of whichcontains the substituent of Q above. Preferably, but not necessarily, isused an excess of the aldehyde based upon the amountv of vinylacetophenone units present in the polymer molecule.

As described above, specific methods include acetylating, eitherpartially or fully, aromatic nuclei of a styrene polymer (homopolymer orcopolymer) and thenv con densing acetyl groups thereof with abenzaldehyde, or naphthaldehyde. Alternately, an acetylated styrenecopolymer is obtained by copolymerization of a mixture of a vinylacetophenone with a compound containing a polymerizable -CH:CH or CH2=Cgroup followed by condensing acyl groups of the copolymer with theselected nuclear-substituted aromatic aldehyde. Other acetylcontainingpolymers are utilized similarly.

Condensation of the vinyl acetophenone or acetonaphthone polymer withthe aldehyde is carried out in the presence of a dehydration catalystsuch as acetic anhydride, phosphorous pentoxide, toluene sulfonic acid,mineral acid, for example, sulfuric acid, phosphoric acid, etc., and thebasic condensation catalysts particularly organic bases such as thequaternary ammonium bases, for example, trimethyl benzyl ammoniumhydroxide, tetramethyl and tetraethyl ammonium hydroxides, tetraethanolammonium hydroxide and trimethyl benzyl ammonium butoxide.

As will be apparent from the following examples given as illustrative ofthe methods of our invention, condensation with the aldehyde ispreferably conducted in the presence of a diluent, which should be asolvent for both the vinyl acetophenone or naphthone polymer, and thealdehyde in use, such as acetic acid, 1,4-dioxane or ketones such asbenzophenone, etc. It is particularly desirable to use as the solventlarge excesses of the aldehyde in addition to the primary solvent, or asin Example 2 to use only the aldehyde reactant as solvent whichincreases the amount of acetyl groups reacted with the aldehyde. It isadvisable to use a diluent, otherwise in some cases the product tends todecrease in solubility during the course of the condensation. It ispossible to employ as the diluent the original diluent used when makingthe vinyl acetophenone polymer or copolymer. That is, when vinylacetophenone etc., is homopolymerized or copolymerized with anotherpolymerizable compound in a diluent, the polymer need not be isolatedbut the polymerization mixture can immediately be reacted with thedesired aldehyde without removal of the diluent. Any unpolymerizedmonomer which may remain in the polymerization mixture does no harm whenthe condensation is subsequently carried out in its presence. As asource of the aldehyde for the condensation reaction may be used thepure aldehydes or mixtures of two or more aldehydes can be used and thealdehyde may be furnished by an acetal, for example, a substitutedbenzaldehyde acetal, or the diacetate may be used. These compoundsreadily decompose in the presence of the condensation catalyst to yieldthe corresponding aldehyde.

In the following table are tabulated the comparative speed values forpolymers made by condensing various aldehydes with selected vinylacetophenone polymers.

Vinyl Ace- Example tophenone Benzaldehyde Speed Polymer 2 VaeP i-CaH1280 3 VacP o-OCH: 1, 600 500 o-OGHa 2, 800 500 1, 000 l0 32 ol 400p-CHaO ONH- 140 p-CH O0NH 7 O-SOsH (Na salt) 16; 200 0-0 CH3 r O-OCHsand benzaldehyda. 13, (100 O CH: 1. 65 3,4-di-OCH3 a-naphthaldehyde 22VaeP OCH3 1 Polyvlnylacetophenone (Example 1). 1 Copolymer withisobutylene.

1 Copolymer with styrene.

4 Partially aeetylated styrene.

In comparing the speeds of the polymers in the above table, it should benoted the mol percent of the lightsensitive groups in the polymersundoubtedly varies, since the aldehydes appear to vary in theirreactivity with the acyl group of the polymers. Thus the polymer ofExample 20 is considered to be fully reacted with the aldehydes andcontains substantially no unreacted acetyl groups. A reduction in speedof this mixed benzalanisal styrene polymer is obtained by decreasing thereaction time to introduce fewer benzal and anisal groups into thepolymer molecule. Example 22 also provides a polymer free of unreactedacetyl groups Example 1 .T he preparation of polyvinyl acetophenone Inan all glass vessel equipped with efficient stirrer, dropping funnel andreflux condenser was placed 268 g. (2 mols.) of finely divided anhydrousaluminum chloride and 1 liter of carbon disulfide. T o the constantlystirred suspension was added 118 g. (1 /2 mol.) of acetyl chloridefollowed by a solution of 104 g. (1 mol.) of polystyrene in 1 liter ofcarbon disulfide. Addition of the polymer solution took about 15minutes. The reaction mixture became warm and refluxed gently, withcopious evolution of hydrogen chloride. No artificial heating or coolingwas used. After about /2 hour the evolution of hydrogen chloride hadgreatly diminished, but stirring was continued another hour. Thereaction mixture was then filtered by suction, about 75% of the carbondisulfide used was thus recovered, and the residue on the filterconsisted of highly swollen discrete particles. These Were dried rapidlyin a gentle current of air to give a dusty yellow powder, which wasthoroughly agitated with cold 5% hydrochloric acid for about 15 minutes.The polymer was filtered ofi and washed by stirring in several changesof cold water. On drying at 40-50 C. there was obtained 142-144 g. of afine, white powder of low ash content. The analysis of this productshowed a carbon content of 81.9% and a hydrogen content of 6.9%. Thecalculated values for pure polyvinyl acetophenone are C=82.2%, H=6.85%.

The above polymer proven to consist essentially ofpolyvinyl-p-acetophenone, may be further purified by dissolving it inacetone and pouring the colorless, slightly hazy solution into an excessof agitated water. The white, fibrous precipitate is again washed withwater and dried. Found C2823, H:7.0.

The other acylated nuclear-substituted styrene and vinyl naphthalenepolymers indicated above are prepared in this manner from theappropriate styrene or vinylnaphthalene polymer, or can be obtained bypolymerizing 0-, mor p-vinylacetophenone and acetonaphthones prepared bythe method of the Williams invention above.

Example 2.C0ndensati0n of polyvinyl acetophenone with p-isopropylbenzaldehyde Five grams of polyvinyl acetophenone were dissolved in g.of p-isopropyl benzaldehyde. To this was added 5 g. of a. 10% (byweight) solution of concentrated sulfuric acid in p-isopropylbenzaldehyde. After standing at room temperature (75 F.) in a brownbottle for eighteen hours the solution was poured into an excess ofstirred methanol. The slightly yellow, fibrous precipitate was leachedin a number of changes of methanol, then dried in the dark at roomtemperature. The precipitate was redissolved in methyl ethyl ketone andagain precipitated into methanol. Yield was 6.5 grams. Sensitometricevaluation indicated that this product had a speed of about 280.

Example 3.C0ndensation of polyvinyl acetophenone with anisaldehyde Fivegrams of polyvinyl acetophenone were dissolved in cc. of glacial aceticacid containing 16 g. of anisaldehyde. To this was added 5 g. of a 10%(by weight) solution of concentrated sulfuric acid in glacial aceticacid and the solution was kept in a brown bottle at room temperature (75F.) for twenty-four hours. The solution was then poured into a largeexcess of agitated ethyl alcohol, the precipitate leached in severalchanges of alcohol, pressed out and dried at room temperature. Yield was5.8 grams. This was redissolved in methyl ethyl ketone and the solutionprecipitated into excess alcohol and dried in the dark. The product hada methoxyl content of 3.9% indicating that the content of p-methoxybenzal vinyl acetophenone was 21.6 mol. percent. Sensitometrically thissample showed a speed of about 2500.

When the above procedure was repeated but employing a reaction time ofsixteen hours, a product was obtained which showed a speed of 1600.

Example 4.Cndensati0n of polyvinyl acetophenone with anisaldehyde Fivegrams of polyvinyl acetophenone were dissolved in 100 g. ofanisaldehyde. To this was added g. of a (by weight) solution ofconcentrated sulfuric acid in glacial acetic acid and the solution wasstored in a brown bottle at room temperature (75 F.-). After twenty-fourhours the very dark red solution was poured into a large excess of ethylalcohol, and the yellow precipitate was leached in several changes ofethyl alcohol, then pressed out and redissolved in methyl ethyl ketonecontaining a little anisaldehyde and reprecipitated into alcohol. Driedin the dark at room temperature. Yield was 7 grams This material showeda speed of 2800. When a-naphthaldehyde and B-methoxy-a-naphthaldehydewere used instead of anisaldehyde polymers of high light-sensitivitywere obtained.

Example 5.Condensation of polyvinyl acetophenone and veratraldehyde 5.0grams of polyvinyl acetophenone were dissolved in a mixture of 80 g. ofglacial acetic acid and g. of veratraldehyde. To this was added 10.0 g.of a 10% (by weight) solution of concentrated sulfuric acid in glacialacetic acid. After 5 /2 hours the reddish dope was poured in a thinstream into an excess of stirred methanol. The

' orange, fibrous precipitate was filtered oifand after expressingsurplus methanol was redissolved in methyl ethyl ketone. This solutionwas poured into excess methanol. Again the precipitate was squeezed outand reprecipitated from methyl ethyl ketone solution into methanol, thenpressed out and dried in the dark at room temperature. This materialpossessed a speed of about 2500.

Example 6.-Cona'ensation of polyvinyl acetophenone with p-hydroxybenzaldehyde Ten grams of polyvinyl acetophenone were dissolved in 180g. of glacial acetic acid containing g. of p-hydroxy benzaldehyde. Tothis wasadded 10 g. of a 10% (by weight) solution of concentratedsulfuric acid in glacial acetic acid, and the solution was allowed tostand in a brown bottle at room temperature (75 F.) After- 5 /2 hoursthe reddish solution was poured in a thin stream into excess, agitatedalcohol. The fibrous precipitate was leached in several changes of freshalcohol, then pressed out and dried at room temperature. The product wasredissolved in methyl ethyl ketone and this solution was poured intoagitated, excess alcohol. The product, a very slightly yellow, fibrousprecipitate, was dried in the dark at room temperature and weighed 11grams. I This polymer exhibited a speed of 1000.

Example 7.-C0ndensation of polyvinyl acetophenone and p-dimethylaminobenzaldehyde 5.0 grams of polyvinyl acetophenone were dissolved in amixture of 10 grams of p-dimethylamino benzaldehyde and 90 g. ofbenzophenone at 50 C. With the solution at C. there was added to it 1.0ml. of 40% solution of trimethyl benzyl ammonium hydroxide with vigorousstirring. After exactly three minutes at 40 C. a slight Example 8.-Conden.ration of polyvinyl acetophenone and p-dimethylaminobenzaldehyde 5.0 grams of polyvinyl acetophenone were mixed with 10 g.of p-dimethylamino benzaldehyde and g. of benzophenone. The mixture wasstirred at 50 C. to give a clear, yellow dope. To this was added .5 g.of a 10% solution (by weight) of concentrated sulfuric acid in glacialacetic acid. This was kept in a brown bottle at 50 C. for twenty-threehours. The resulting product was then poured in a thin stream into anexcess of stirred methanol. The yellow, rubbery precipitate was pressedout and redissolved in methyl ethyl ketone. The solution was againpoured slowly into an excess of methanol. The precipitate wasredissolved in methyl ethyl ketone and this time the solution was pouredslowly into agitated. warm water to give a yellow, fibrous polymer whichwas leached in fresh, warmwater, pressed out and dried at roomtemperature. This polymer displayed a speed of 32.

Example 9. C0nzlensati0n of polyvinyl acetophenone witho-chlorobenzaldehyde Five grams of polyvinyl acetophenone were dissolvedin a mixture of cc. of glacial acetic acid and 18 g. ofo-chlorobenzaldehyde. To this was added 5 g. of a 10% (by weight)solution ofconcentrated sulfuric acid in glacial acetic acid. Thesolution was stored in a brown bottle at room temperature (75 F.). Aftertwenty-one hours the solution was poured slowly into an excess ofstirred alcohol. The white precipitate was filtered off, and thensqueezed out. This was leached in several changes of ethylalcohol anddried at room temperature in subdued light. The polymer was then twicemore dissolved in methyl ethyl ketone and precipitated by pouring thesolution into excess of ethyl alcohol. The white, fibrous precipitatewas pressed out and dried in subdued light. The sample contained 4.9% ofchlorine indicating a 24.3 mol. percent content of the o-chlorobenzalacetophenone. The polymer when evaluated sensitometrically showed aspeed of 400.

Example 10.-Condensati0n of polyvinyl acetophenone and p-acetaminobenzaldehyde Five grams of polyvinyl acetophenone were mixed with 10 g.of p-acetamino benzaldehyde and 75 cc. of glacial acetic acid. This wasstirred until a clear solution was obtained, whereupon there was added 5g. of a 10% solution (by weight) of concentrated sulfuric acid inglacial acetic acid and the solution was allowed to stand in a brownbottle at room temperature (75 F.). After twenty hours the product waspoured in a thin stream into an excess of stirred methanol. The brightyellow, fibrous precipitate was leached in fresh methanol, pressed outand redissolved in methyl ethyl ketone. The solution was againprecipitated into excess methanol and the precipitate pressedout andredissolved in methyl ethyl ketone. This solution was finally pouredinto an excess of agitated warm water and the yellow fibrous precipitatewas dried at room temperature. The polymer exhibited a speed of whenevaluated sensitometrically.

Example 11.Condensation of polyvinyl acetophenone and p-acetaminobenzaldehyde benzyl trimethyl ammonium hydroxide were added. Afterexactly five minutes of stirring there was added a slight excess ofglacial acetic acid to neutralize the alkali present. The solution waspoured slowly into an excess of stirred methanol. The precipitate wasagain precipitated from methyl ethyl ketone into methanol and finallyprecipitated from methyl ethyl ketone into warm water. The white,fibrous polymer was dried at room temperature. The polymer showed aspeed of 7.

Example 12.Cndensati0n of polyvinyl acetophenone and sodiumo-sulfobenzaldehyde Five grams of polyvinyl acetophenone was dissolvedin a solution of g. of sodium o-sulfobenzaldehyde and 75 cc. of glacialacetic acid. To the clear solution was added 10 g. of a 10% (by weight)solution of concentrated sulfuric acid in glacial acetic acid. Theresulting solution was stored in a brown bottle at 30-32 C. for eighthours, at the end of which time the product was poured in a thin streaminto distilled water. The white, fibrous precipitate was thoroughlywashed with distilled water and then dried at room temperature. Theproduct was not soluble in acetone but was readily soluble in mixturesof acetone and water. Sensitometrically it showed a speed of 16.

Example 13.Preparation of a copolymer of vinyl acetophenone andisobutylene Gne-hundred sixty grams of a copolymer of styrene andisobutylene (consisting of essentially equimolecular proportions of thetwo monomers) were dissolved in 1 liter of carbon disulfide. In a 5 l.flask fitted with an eflicient glass stirrer, condenser and droppingfunnel was suspended 268 g. of anhydrous aluminum chloride in 1 liter ofcarbon disulfide. To this was then added 118 g. of acetyl chloride.While this suspension was well stirred, the solution of the polymer wasadded over a period of ten minutes. Copious evolution of hydrogenchloride took place and a loose bulky precipitate formed. After theaddition of the polymer was complete, stirring was continued for anotherhour. The product was filtered and the crumbly polymer dried in acurrent of air. The dried polymer was crushed up fine and stirred upwith an excess of ice cold 5% hydrochloric acid solution. The polymerwas filtered off by suction and washed thoroughly with water to removeexcess acid. Dried at 40 C. Yield about 180 grams.

Example 14.C0miensotion of a copolymer of vinyl acetophenone andisobutylene with anisaldehyde Ten grams of a copolymer of vinylacetophenone and isobutylene (made as above) were dissolved in a mixtureof 160 cc. dioxane and g. anisaldehyde. To this was then added withstirring, a solution of 1.0 g. of concentrated sulfuric acid in 10 cc.of dioxane. After twentythree hours at room temperature the resultingsolution was poured into excess stirred methanol, the slightly soft,fibrous precipitate being leached in fresh methanol, then pressed outand redissolved in dioxane. This solution was again poured into'excess,agitated methanol. The precipitate was again dissolved in dioxane andthis time precipitated into warm water. The white, rubbery polymer wasleached in fresh water, then squeezed out and dried in the dark at roomtemperature. This material was light-sensitive.

A copolymer of styrene and vinyl acetophenone can be prepared in twoways: (1) by the copolymerization of styrene and vinyl acetophenone and(2) by the incomplete acetylation of polystyrene by acetyl chloride inthe presence of anhydrous aluminum chloride. The following examplesdemonstrate the two procedures and the subsequent condensations of theproducts obtained with aromatic aldehydes.

Example 1 5 .T he preparation of monomeric vinyl acetophenone Polyvinylacetophenone (prepared by the reaction of acetyl chloride on polystyrenein the presence of anhydrous aluminum chloride, as described in theKenyon et al. U. S. application, Serial No. 246,519, filed concurrentlyherewith) was heated in a distilling apparatus with the bare flame of agas burner, the system being evacuated to 1 mm. pressure. yield of alight brown oil was obtained which readily crystallized on chilling.This product was redistilled and a very pale yellow oil was collectedwhich distilled at 9398 C. at 0.5 mm. Hg pressure.

The distillate crystallized and this was recrystallized twice fromligroin (B. P. 6090 C.) by chilling the solution thoroughly. Whitecrystalline plates were obtained which melted at 34 C. Titration of asample of this for double bond by means of bromine indicated a 98.9%content of vinyl acetophenone.

The isomeric vinyl acetophenones and acetonaphthones can also beprepared by the methods of the mentioned Williams invention. That methodis used in particular when preparing the monomeric ketones the arylnucleus of which is substituted with groups such as hydroxyl, amino,sulfa and carboxyl.

Example I6.The copolymerization of vinyl acetophenone with styrene Fivegrams of vinyl acetophenone were mixed with 3.6 g. of freshly distilledstyrene together with 0.043 g. of benzoyl peroxide and 25 cc. of methylethyl ketone. This solution was refluxed gently on the steam bath fortwenty-four hours. The resulting viscous, clear, colorless solution waspoured into an excess of agitated methanol. The while, friable polymerwas leached in fresh methanol, then dried at 40 C. Found C=84.1%, H:7.2%. Calculated C, 86.4%; H, 7.2%.

Example 17.C0ndensation of copolymer of styrene and vinyl acetophenonewith anisaldehyde Four grams of the copolymer of vinyl acetophenone andstyrene were dissolved in 20 cc. of glacial acetic acid together with 10g. of anisaldehyde. Two grams of a 10% solution (by weight) ofconcentrated sulfuric acid in glacial acetic acid were then added. Aftertwenty-three hours standing in a brown bottle at room temperature theresulting solution was poured into an excess of stirred methanol. Theprecipitate was leached in fresh methanol. The precipitate was thereuponprecipitated twice from methyl ethyl ketone solution into methanol. Awhite, friable precipitate was obtained. Speed=65.

Example 1 8.T he preparation 0; a partially acetylated polystyreneFifty-two grams of polystyrene were dissolved in 500 cc. of carbondisulfide. This was added to a suspension of 62 g. of anhydrous aluminumchloride in 500 cc. of carbon disulfide contained in a 3-liter glassflask fitted with an efiicient glass stirrer, condenser and droppingfunnel. While the mixture was being vigorously stirred, a mixture of 30g. of acetyl chloride and cc. of carbon disulfide were added dropwise.During this addition the reaction mixture soon became thick andgelatinous and another 500 cc. of carbon disulfide were added. Stirringwas continued and more of the acid chloride mixture was cautiously addedand soon the gel structure collapsed and a suspension of highly swollenpolymer particles suspended in the carbon disulfide was obtained. Theremainder of the acid chloride could now be added at a faster rate.Copious evolution of hydrogen chloride was observed and stirring wascontinued for another hour after the addition of the acid chloride wascomplete. The mixture was then filtered and dried in a current of air.The crumbly product was broken up fine and added to a Well-stirred icecold 5% hydrochloric acid solution.

The white suspension was filtered OE and washed with water and dried.The White, dry polymer was dissolved in dioxane, the solution filteredand the filtrate was poured slowly into an excess of agitated methanol.The white, fibrous precipitate was washed throughly in water, then driedat 40 C.

Example 19.Cndensati0n of a partially acetylated polystyrene withveratraldehyde Ten grams of partially acetylated polystyrene, preparedas above, were dissolved in 150 g. of dry dioxane and 25 g. ofveratraldehyde. To this was added g. of a 10% (by weight) solution ofconcentrated sulfuric acid in glacial acetic acid. The solution wasstored in a brown bottle at room temperature (25 C.) for 7 /2 hours. theend of this period the solution was poured in a thin stream intoagitated, excess methanol. The tan, fibrous precipitate was filteredoff, leached in fresh methanol and redissolved in methyl ethyl ketone.This solution was again poured into excess methanol and the fibrousprecipi ..i

tate 'was filtered off and finally precipitated again from methyl ethylketonesolution into hot water. This polymer was light-sensitive.

Example 20.C0ndensati0n of polyvinyl acetophenone with a mixture ofbenzaldehyde and anisaldehyde Ten grams of polyvinyl acetophenone weredissolved in a mixture of 78 g. ofbenzaldehyde and 112 g. ofanisaldehyde, and to this was added 10 g. of a 10% solution (by weight)of concentrated sulfuric acid in benzaldehyde. The product was allowedto stand in a brown bottle at room temperature (3032 C.) for 97 hours.Thereupon the reddish solution was poured slowly into excess of stirredmethanol. The precipitate was then redissolved in methyl ethyl ketonecontaining some benzaldehyde. Once more the precipitate was redissolvedin a mixture of methyl'ethyl ketone and benzaldehyde and precipitatedagain into methanol. The precipitate was leached in fresh methanol andair dried in dark. The sensitometric speed of this material was 13000.

g It is not understood why this synergistic effect is obtained i. e.,neither vinyl benzal or anisal acetophenone, polymers alone possessspeed in this range.

Example 21.The condensation of polyvinyl acetophenone with sodiumo-sulfo-benzaldehyde Five grams of polyvinyl acetophenone were dissolvedin a mixture of 80 cc. of dioxane and cc. of alcohol. Ten grams ofsodium o-sulfobenzaldehyde (the technical product was twicerecrystallized from alcohol) were added to the stirred solution. Witheflicient stirring there was added to the slurry 20g. of a solution madeup of one part by weight of a 40% aqueous trimethylbenzyl ammoniumhydroxide solution and 19 parts of water. The addition was made dropwiseover a period of 10 minutes.

The resulting solution was clear, but after 30 minutes it began to showcloudiness. Five cc. of water were added to clear it, followed byanother 5 cc. 30 minutes later. After standing for a total of two hoursat room temperature the solution was acidified with a little acetic acidand poured into an excess of acetone. The precipitate was filtered ofiand redissolved in water containing a little acetone. Again the solutionwas poured into excess acetone. The precipitate was then leached infresh acetone, filtered off and dried in vacuo. The product was solublein (by weight) of acetone in water or a solution (by weight) of alcoholin water. The

. polymer contained 5.9% sulfur (41.4 mol percent) of sodiumo-sulfabenzalacetophenone groups. Speed=200.

Example 22.C0ndensati0n of polyvinylacetophenone with anisaldehyde Thispolymer was obtained by fully reacting the acetyl groups of polyvinylacetophenone with anisaldehyde as follows:

Five grams of polyvinylacetophenone were dissolved in 150 grams ofanisaldehyde and to this was added 15 grams of a 10% (by weight)solution of concentrated sulfuric acid in glacial acetic acid. This wasallowed to stand in the dark for hours at 25-30 C. Thirty grams of a 10%sodium acetate solution in glacial acetic acid were stirred into thissolution which was further diluted with methyl ethyl ketone. Thissolution was poured into an excess of stirred methanol, the precipitateleached in fresh methanol, then was thoroughly washed in running coldwater. The product was dried in the dark at room temperature. Yield=9grams and the product possessed a methoxyl content of 11.6% indicatingthat sub-Q stantially no unreacted acetyl groups were contained in thepolymers. The polymer possessed a high degree oflight-sensitivity.

In addition to the vinyl acetophenone polymers given in the aboveexamples can be used acylated polymers, e. g. of d-methyl-, m-methyl-,2,5-dimethyl-, ethyl- 0- hydroxy-, o-, m-, p-chloroor bromo-, p-benzyl-,3,4- dichloro, 3,4-dimethoxy, m-tert. butyl-styrenes, oand m-methoxystyrenes, p-phenoxy styrene, etc., and copolymers of mixtures of 5-95mol percent of these acylated styrenes or of these styrenes polymerizedwith polymerizable compounds such as styrene, acrylonitrile, vinylacetate, vinyl ethers, acrylic and alkacrylic acids and esters, maleicanhydride, etc. The homologous vinyl propiophenone etc. polymers are ofless value for the preparation of light-sensitive polymers. However,copolymers containing both vinyl acetophenone and vinyl propiophenoneunits are very useful in the invention.

In general the polymer reacted with the aldehyde need only contain aselected proportion, 100 mol percent or less, of the indicatedCO(CH2)n-1CH3 groups n=1 to 4. To this end the vinyl ketone polymerssuch as methyl vinyl ketone homoor copolymers with other polymerizablecompounds such as methyl methacrylate, are useful. In this case thearylidene acetyl group obtained is attached directly to carbon chain ofthe polymer rather than indirectly as is the case when the aldehyde isreacted with polymers such as polyvinyl acetophenone.

Results similar to those of the above examples are obtained bycondensing the benzaldehyde as above with homopolymers and copolymers ofthe 0-, mand pacylated styrenes and vinyl naphthalenes prepared by themethods of the Williams invention. For example, substantially nodifference in physical and chemical properties could be detected betweenthe vinyl benzalacetophenone polymer of Example 4 and one obtained fromp-vinylacetophenone (from p-ethylacetophenone) by condensation with thebenzaldehyde. Similarly copolymers of the isomeric acylated vinylbenzenes and naphthalenes behave similarly when condensed with thebenzaldehyde.

The polymers of the invention can be sensitized so as to furtherincrease their sensitivity to light by use of the nitro compounds ofMinsk et al. U. S. patent application Serial No. 148,684, filed March 9,1950, and the triphenylmethane, anthrone, quinone and ketone compoundsof the Minsk et al. applications Serial Nos. 207,048-51, filed January20, 1951, particularly those acylated vinyl benzene and naphthalenepolymers having inherently low light sensitivity before sensitization,of the order of 100. Contrary to this, the light-sensitive polymers ofthe Allen et al. invention above are not sensitized by those compounds.

The polymers of the invention are particularly useful forphotomechanical purposes where it is desired to prepare a resist imageon a given surface. For example, the polymer is coated from solvent upona support such as a metal plate, paper, or organic colloid surface; forexample, especially upon a surface which when moistened repels greasyprinting inks, such as a lithographic paper plate, and after exposure tothe desired line or halftone subject, the unexposed areas are dissolvedaway, leaving a resist image on the original support; At this stage, if

the resist has been formed on a surface repelling greasy inks whenmoistened, the element can be used directly as a printing plate. Inother cases, the support, such as a metal plate, can be etched out in awell known manner to obtain an etched metal printing plate. Other usesfor our polymers employing their light-sensitive properties will occurto those skilled in the art. For example, the polymers can be employedto form continuous soluble or insoluble coatings on any surface orobject to which they will adhere, in the latter case exposure to lightbeing employed to insolubilize the coating.

The light-sensitive polymers can be used for photographic reproductionof line, half-tone or continuous tone subjects. In the latter case it ispreferable to coat the polymer on a transparent support, expose thecoating thru the support followed by washing away the least exposedareas with solvent leaving a continuous tone relief image on the supportwhich may be colored previously or subsequently with subtractivelycolored dyes for purposes of color photography. Three such subtractivelycolored reliefs corresponding to blue, green and red aspects of asubject can then be superimposed to obtain a natural color reproductionor three such images may be formed on a single support by successivelycoating layers of the polymers, or the support after first formingrelief images thereon corresponding to one or more of the red, green orblue aspects of the original subject. Thus forming a yellow coloredrelief on the support, a layer of polymer is coated thereon and themagenta relief is formed on top of the yellow relief and the cyansimilarly.

In our application Serial No. 246,517, filed concurrently herewith, aredescribed and claimed comparable condensation products of vinylacetophenone and naphthone polymers with benzaldehyde which generallyare less light-sensitive than the vinyl-benzal acetophenone andnaphthone polymers of this invention. However, as is apparent, the mixedaldehyde condensates (benzaldehyde and another aromatic aldehyde) of thepolymers containing acetyl groups possess exceptionally highlightsensitivity.

What we claim is:

1. A process for preparing a polymer which comprises acetylatingaromatic nuclei of a styrene polymer and condensing the resultingpolyvinyl acetophenone polymer with an aromatic aldehyde having thegeneral formula wherein R represents a univalent aromatic monocyclicradical of the benzene series whose free valence belongs to the aromaticnucleus, there being no more than four hydrogen atoms attached directlyto the carbon atoms of said nucleus, in the presence of an acidcondensation catalyst.

2. A process for preparing a polymer which comprises condensing with anaromatic aldehyde having the general formula R-CHO wherein R representsa univalent aromatic monocyclic radical of the benzene series whose freevalence belongs to the aromatic nucleus, there being no more than fourhydrogen atoms attached directly to the carbon atoms of said nucleus, apolymer of a compound having the general formula wherein D represents abivalent aromatic radical whose free valences belong to the aromaticnucleus and which radical is selected from the group consisting ofmonocyclic radicals of the benzene series and bicyclic radicals of thenaphthalene series, in the presence of a condensation catalyst.

3. A process for preparing a polymer which comprises condensing anaromatic aldehyde having the general formula R-CHO wherein R representsa univalent aromatic monocyclic radical of the benzene series whose freevalence belongs to the aromatic nucleus, there being no more than fourhydrogen atoms attached directly to the carbon atoms of said nucleus,with a polymer containing recurring groups having the general formulawherein n represents a positive integer of from 1 to 4 and D representsa bivalent aromatic radical whose free valences belong to the aromaticnucleus and which radical is selected from the group consisting ofmonocyclic radicals of the benzene series and bi-cyclic radicals of thenaphthalene series, in the presence of a condensation catalyst.

4. A process for preparing a polymer which comprises condensing apolymer of an ar-vinyl acetophenone with a mixture of aromatic aldehydeshaving the general formula R-CHO wherein R represents a univalentaromatic monocyclic radical of the benzene series whose free valencebelongs to the aromatic nucleus, there being no more than four hydrogenatoms attached directly to the carbon atoms of said nucleus, in thepresence of a condensation catalyst.

5. A process for preparing a polymer which comprises condensing apolymer of a compound having the general formula wherein D represents amonocyclic arylene group of the benzene series, with an aromaticaldehyde having the general formula RCHO wherein R represents aunivalent aromatic monocyclic radical of the benzene series whose freevalence belongs to the aromatic nucleus, there being no more than fourhydrogen atoms attached directly to the carbon atoms of said nucleus, inthe presence of a condensation catalyst.

6. A process for preparing a polymer which comprises condensing apoly-ar-vinyl acetophenone polymer with an aromatic aldehyde having thegeneral formula R-CHO wherein R represents a univalent aromaticmonocyclic radical of the benzene series whose free valence belongs tothe aromatic nucleus, there being no more than four hydrogen atomsattached directly to the carbon atoms of said nucleus, in the presenceof a condensation catalyst, thereby obtaining a vinyl benzalacetophenonepolymer.

7. A process for preparing a polymer which comprises acetylatingaromatic nuclei of a styrene polymer and condensing the resultingar-vinyl acetophenone polymer with an aromatic aldehyde having thegeneral formula R-CHO wherein R represents a univalent aromaticmonocyclic radical of the benzene series whose free valence belongs tothe aromatic nucleus, there being no more than four hydrogen atomsattached directly to the carbon atoms of said nucleus, in the presenceof a condensation catalyst.

8. A process for preparing a polymer which comprises polymerizing anar-vinyl acetophenone and condensing acetyl groups of the resultingpolymer with the aldehyde group of an aromatic aldehyde having thegeneral formula RCHO wherein R represents a univalent aromaticmonocyclic radical of the benzene series whose free valence belongs tothe aromatic nucleus, there being no more than four hydrogen atomsattached directly to the carbon atoms of said nucleus, in the presenceof a condensation catalyst.

15 9.,A process for preparing a polymer which comprises partiallyacetylating the aromatic nuclei of a styrene polymer and condensingacetyl groups of the resulting polymer with an aromatic aldehyde havingthe general formula RCHO wherein R represents a univalent aromaticmonocyclic radical of the benzene series whose free valence belongs tothe aromatic nucleus, there being no more than four hydrogen atomsattached directly to the carbon atoms of said nucleus, in the presenceof a condensation catalyst.

10. A process for preparing a polymer which comprises polymerizing anar-vinyl acetophenone with an ar-vinyl benzene and condensing acetylgroups of the resulting co-polymer with an aromatic aldehyde having thegeneral formula wherein R represents a univalent aromatic monocyclicradical of the benzene sen'es whose free valence belongs to the aromaticnucleus, there being no more than four hydrogen atoms attached directlyto the carbon atoms of said nucleus, in the presence of a condensationcatalyst;

ll. A process for preparing a polymer which comprises condensing apoly-ar-vinyl acetophenone polymer with an alkoxy benzaldehyde in thepresence of a condensation catalyst. r

12. A process for preparing a polymer which comprises 7 condensing apoly-ar-vinyl acetophenone polymer with anisaldehyde in the presence ofa condensation catalyst.

13. A process for preparing a polymer which comprises condensingpolyvinyl acetophenone with benzaldehyde and anisaldehyde in thepresence of a condensation catalyst.

14. The process of claim 13 wherein the condensation catalyst issulfuric acid.

15. A polymer capable of forming a continuous coat ing on a base andcontaining structure 16. A polymer capable of forming a continuouscoating on a base and containing a mixture of recurring units recurringunits having the OGHa,

References Cited in the file of this patent UNITED STATES PATENTSDAlelio Oct. 26, 1943 ,Novotny et al. July 24, 1951 Allen et al. Sept.4, 1951

2. A PROCESS FOR PREPARING A POLYMER WHICH COMPRISES CONDENSING WITH ANAROMATIC ALDEHYDE HAVING THE GENERAL FORMULA